Prohibit JVM target 1.6

But still compile stdlib, reflect, kotlin.test and scripting runtimes
with JVM target 1.6 to simplify migration from Kotlin 1.6 to 1.7.

 #KT-45165 Fixed

libraries/stdlib/jdk7/build.gradle

@@ -44,6 +44,7 @@ configurations {
 dependencies {
     api project(':kotlin-stdlib')
     testApi project(':kotlin-test:kotlin-test-junit')
+    kotlinCompilerClasspath project(':libraries:tools:stdlib-compiler-classpath')
 }
 
 jar {

libraries/stdlib/jvm-minimal-for-test/build.gradle.kts

@@ -20,6 +20,7 @@ val builtins by configurations.creating {
 dependencies {
     compileOnly(project(":kotlin-stdlib"))
     builtins(project(":core:builtins"))
+    kotlinCompilerClasspath(project(":libraries:tools:stdlib-compiler-classpath"))
 }
 
 sourceSets {

libraries/stdlib/jvm/build.gradle

@@ -63,6 +63,8 @@ dependencies {
     testApi project(':kotlin-test:kotlin-test-junit')
 
     builtins project(':core:builtins')
+
+    kotlinCompilerClasspath project(':libraries:tools:stdlib-compiler-classpath')
 }
 
 jar {